Double guided mud pulse valve

Abstract

The present invention discloses a double guided slide valve apparatus for producing pressure pulses in drilling mud medium flowing through a drill string casing.

What is claimed is: 
     
       1. Apparatus for generating pressure pulses in drilling mud medium flowing through a drill string casing comprising: a tubular casing including a narrow passage therewithin proximate to said tubular casing and a tubular main valve body arranged coaxially in said tubular casing thereby forming an outer flow channel wherein said valve body can move axially from a starting position in a direction opposite to the direction of mud flow into an operating position within said narrow passage so that the flow cross section of the outer flow channel varies as a function of the position of the main valve body with respect to said narrow passage;   a tubular supporting body arranged coaxially within said main valve body and including a first slide guide for the down stream end of said main valve body, said supporting body including an internal flow channel having an inlet opening located upstream of said narrow passage at the end of a projection from said supporting body, said projection having a diameter smaller than the diameter of said narrow passage and an outlet opening at the downstream end of said supporting body selectively closeable by a valve, said projection further including a second slide guide for the upstream end of said main valve body; and   a pressure chamber formed between the projection and the main valve body, said chamber connected by connecting channels to said internal flow channel.   
     
     
       2. The apparatus of claim 1, wherein said first and second slide guides include a hard coating. 
     
     
       3. The apparatus of claim 2, wherein said hard coating is comprised of tungsten carbide. 
     
     
       4. The apparatus of claim 1, wherein said internal flow channel inlet opening is formed by a plurality of laterally aligned boreholes on the upstream end of said projection. 
     
     
       5. The apparatus of claim 4, wherein a screen means is placed in front of said plurality of boreholes and said screen means is coaxially aligned and essentially flush with said projection. 
     
     
       6. The apparatus of claim 5, wherein said boreholes open into an annular space behind said screen means. 
     
     
       7. The apparatus of claim 1, wherein a safety stop for said main valve body is provided between the upstream end of said projection and the second slide guide. 
     
     
       8. The apparatus of claim 4, wherein a safety stop for said main valve body is provided between the upstream end of said projection and the second slide guide. 
     
     
       9. The apparatus of claim 8, wherein said safety stop associated with an attachment part at the upstream end of said projection. 
     
     
       10. The apparatus of claim 9, wherein said attachment part includes a coupling means for a pulling tool. 
     
     
       11. The apparatus of claim 9, wherein said internal flow channel extends into said attachment part, and said laterally aligned boreholes extend through said attachment part to communicate with said internal flow channel. 
     
     
       12. An apparatus for generating pressure pluses in a flow of drilling fluid through a wellbore, comprising: a tubular casing for receiving said fluid flow and including a circumferential constriction on the interior thereof;   a supporting body coaxially mounted in said casing having a projection thereon extending through said casing constriction;   a selectively closeable internal flow channel within said supporting body extending into said projection having an inlet opening above said casing constriction and an outlet opening therebelow;   one or more connecting channels extending from said flow channel to the exterior of said supporting body between said inlet and outlet openings;   a substantially tubular main valve body longitudinally slidingly mounted on said support body adjacent said casing constriction, said support body and said main valve body defining a chamber therebetween in communication with said one or more connecting channels.   
     
     
       13. The apparatus of claim 12, wherein said main valve body slides on a first slide guide disposed on said projection, and a second slide guide disposed on said support body below said projection. 
     
     
       14. The apparatus of claim 13, further including valve body safety stop means associated with said projection, adopted to prevent said main valve body from moving beyond a predetermined distance from said constriction. 
     
     
       15. The apparatus of claim 12, wherein said internal flow channel is selectively closeable by an auxiliary valve disposed at the end of said support body opposite said projection.